The present invention relates to a material designed to provide a pleasant thermal environment by relieving summer heat, and more specifically to a low-emission skin material for a vehicle interior trim component, which can prevent not only a temperature rise in the interior trim component but also heat radiation therefrom to the interior and occupant of a vehicle even when the vehicle is parked in the hot sun.
The interior of a parked vehicle reaches a high temperature in the hot sun. It is reported that the temperature of the vehicle interior is elevated to about 70° C. with interior trim components e.g. an instrument panel and a ceiling thereof heated to about 100° C. and to about 70° C., respectively, while the vehicle is parked under the scorching sun in Japanese summer. Needless to say, it is unpleasant to ride in such a vehicle. In addition, the heated interior trim components emit radiant heat therefrom over an extended time period so that the vehicle interior and the interior trim components cannot be easily cooled by ventilation and air conditioning. The air conditioning thus results in excessive energy consumption.
In order to address the above problems, Japanese Laid-Open Patent Publication No. 9-295509 proposes a system for ventilating a vehicle interior by the use of a solar battery. However, the proposed ventilation system only allows one part of the vehicle interior to be ventilated, and does not provide practical solutions to the problem of radiant heat being emitted from the interior trim components.
For the purpose of preventing temperature rises in vehicle interior trim components, Japanese Laid-Open Patent Publication No. 2001-158306 proposes a heat shield system that comprises a heat-wave reflection layer provided between a roof panel and a roof lining so as to reflect sunlight and thereby keep heat from coming into a vehicle interior through the roof panel. The proposed heat shield system prevents a temperature rise in a vehicle ceiling to some degree, but cannot eliminate the heat transfer paths over which sunlight gets into the vehicle interior through window glasses and is then reflected by and absorbed in interior trim components such as an instrument panel to cause heat radiation therefrom. Accordingly, the temperature rise preventing effect of the heat shield system is very limited.
Japanese Laid-Open Patent Publication No. 5-193668 proposes a laminate film for e.g. a refrigerator rather than automotive applications. Although the proposed laminate film attains an improved heat insulating property and a low thermal emissivity, the laminate film cannot be suitably used for a vehicle interior trim component for lack of decorativeness.
It is desired that the vehicle interior trim components are prevented from rising in temperature and, if unavoidably rise in temperature, emitting radiant heat therefrom to the vehicle interior and occupant, and are capable of providing a decorative effect for the vehicle interior. For example, the vehicle interior trim components are generally colored in gray. In the case of the interior trim component being made of a fibrous substance, the interior trim component can be colored by e.g. kneading a white inorganic pigment (such as titanium oxide) into fiber or dyeing the fibrous substance. Opaque dull fiber in which white inorganic pigment (such as titanium oxide) is kneaded may be mixed or blended in order to adjust the color tone of the interior trim component and prevent the occurrence of see-through sections in the interior trim component. However, the interior trim component colored with an inorganic pigment absorbs not only visible radiation but also infrared radiation that is originally irrelevant to decorativeness, and then, converts the absorbed visible and infrared radiation into heat. It is thus difficult to prevent a temperature rise in the interior trim component and heat radiation therefrom.